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20 E. Imbert Fig. 1. Phylogenetic relationship among the 27 sections of the genus Crepis according to Babcock (1947). For section 15, the relations are numerous, and thus are not represented. For each section, the number of species is given; “H” symbolizes the presence of at least one heterocarpic species within the section. Babcock (1947) produced a monograph of this genus describing 196 species. Based on this study, 30 species can be considered as heterocarpic. In the Appendix, however, 28 Crepis species only are listed because two species described by Babcock are no longer recognised (C. cretica and C. corymbosa, see the Global Provisional Checklist). Because this review is based on the phylogenetic structure with 27 sections within the genus proposed by Babcock (1947, Fig. 1), it uses also the respective taxonomy. Although the phylogeny suggested by Babcock (1947) may change with time, it can still Perspectives in Plant Ecology, Evolution and Systematics (2002) 5, 13–36 be used to test a phylogenetic pattern in seed heteromorphism. To test for association between annual life cycle and seed heteromorphism, species were arranged in two classes: monocarpic (annual and biennial species) and polycarpic (perennial species). For the relationship between habitats and seed heteromorphism, habitats were first classified in dry habitats (including desert, sclerophyllous communities, rocky and sandy places) and wet habitats (river verges, grassland, deciduous and tropical forests). In a second step, to test for an association between predictability of habitats
and presence/absence of seed heteromorphism, species were arranged in five classical biogeographical areas (mediterranean, desert, tropical, continental, and temperate) assuming a greater unpredictability in mediterranean and desert areas than in other biomes, which is commonly stated in particular for annual precipitations (Ellner & Shmida 1981; Petit 1990). Mountains were added as a sixth biogeographical unit, and species were included in this category when their distribution were limited to mountainous habitats; this biome was Consequences and ontogeny of seed heteromorphism 21 Fig. 2. The relationship between presence/absence of heterocarpy and life cycle (monocarpic or polycarpic) in Crepis according to the phylogenetic relationship among the 27 sections (from Babcock 1947). “H” symbolizes the presence of at least one heterocarpic species in the section. Box with full lines, all species polycarpic; box with bold lines, all species monocarpic; and box with broken lines, the section contains both monocarpic (M) and polycarpic (P) species. Numbers represent section numbers (cf. Fig. 1). considered as predictable. Crepis species were sorted according to the description given by Babcock (1947). No statistical test was used since the data cannot be considered as independent. The heterocarpic species belong to 12 different sections, and it can be suggested that seed heteromorphism has evolved independently several times within the genus (Fig. 1). However, heterocarpy and monocarpy seem to be associated (Fig. 2). For instance, in section 20 (9 spp.) and section 26 (7 spp.) all species are monocarpic and these Perspectives in Plant Ecology Evolution and Systematics (2002) 5, 13–36
Page 1 and 2: Vol. 5/1, pp. 13-36 © Urban & Fisc
Page 3 and 4: 250,000 angiosperm species, the pre
Page 5 and 6: melina benghalensis (Commelinaceae;
Page 7: quence of seed heteromorphism (Harp
Page 11 and 12: Table 3. Number of heterocarpic and
Page 13 and 14: ner & Shmida 1984) and Bidens pilos
Page 15 and 16: Bachmann K & Price HJ (1979) Variab
Page 17 and 18: Gutterman Y (1994) Long-term seed p
Page 19 and 20: Ruiz de Clavijo E (1994) Heterocarp
Page 21 and 22: Appendix Consequences and ontogeny
Page 23 and 24: Family Species References Consequen

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